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The tolerable upper intake level (UL), or upper limit, for selenium is 400 mcg a day for everyone 14 and older. That is the most a day that is unlikely to cause harm for almost everyone; above it, the chance of side effects goes up. It is a ceiling, not a target. The limit counts selenium from food, water and supplements together.
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Servings a day
This limit is the same for everyone 14 and older, including pregnancy and breastfeeding.
Type the amount from your label to compare it with the upper limit.
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Selenium upper limits by age
| Age | Males | Females | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Birth to 6 months | 45 mcg | 45 mcg | – | – |
| 7-12 months | 60 mcg | 60 mcg | – | – |
| 1-3 years | 90 mcg | 90 mcg | – | – |
| 4-8 years | 150 mcg | 150 mcg | – | – |
| 9-13 years | 280 mcg | 280 mcg | – | – |
| 14-18 years | 400 mcg | 400 mcg | 400 mcg | 400 mcg |
| 19-30 years | 400 mcg | 400 mcg | 400 mcg | 400 mcg |
| 31-50 years | 400 mcg | 400 mcg | 400 mcg | 400 mcg |
| 51-70 years | 400 mcg | 400 mcg | – | – |
| 71+ years | 400 mcg | 400 mcg | – | – |
How much Selenium you need
| Age | Males | Females | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| Birth to 6 months | 15 mcg* | 15 mcg* | – | – |
| 7-12 months | 20 mcg* | 20 mcg* | – | – |
| 1-3 years | 20 mcg | 20 mcg | – | – |
| 4-8 years | 30 mcg | 30 mcg | – | – |
| 9-13 years | 40 mcg | 40 mcg | – | – |
| 14-18 years | 55 mcg | 55 mcg | 60 mcg | 70 mcg |
| 19-30 years | 55 mcg | 55 mcg | 60 mcg | 70 mcg |
| 31-50 years | 55 mcg | 55 mcg | 60 mcg | 70 mcg |
| 51-70 years | 55 mcg | 55 mcg | – | – |
| 71+ years | 55 mcg | 55 mcg | – | – |
* Adequate Intake (AI): the amount set when there isn’t enough evidence for an RDA.
What counts toward the Selenium limit
The limit counts selenium from food, water and supplements together.
What happens with too much Selenium
The National Academies based the adult UL of 400 micrograms a day on selenosis (chronic selenium toxicity), selecting "hair and nail brittleness and loss" as the critical endpoints. The no-observed-adverse-effect level of 800 micrograms a day came from a reexamination of five people in China who had previously shown signs of selenosis (Yang and Zhou, 1994), and an uncertainty factor of 2 was applied to protect sensitive individuals, because the effect is not severe but may not be readily reversible. Besides hair and nail changes, the report says other reported signs of chronic selenosis include gastrointestinal disturbances, skin rash, "garlic breath odor," fatigue, irritability and nervous system abnormalities.
Sources: National Academies, Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids (2000); Health Canada, Dietary Reference Intakes tables (the joint U.S.-Canada values). Limits checked November 8, 2026. More from the NIH: Office of Dietary Supplements Selenium fact sheet.
If you think you or a child took too much of a supplement, call Poison Control at 1-800-222-1222 (U.S., free, 24 hours) or use poison.org. In an emergency, call 911.
General information, not medical advice. Your doctor may recommend a different amount, for example to treat a deficiency. Talk to your doctor or pharmacist before you start, stop or change a supplement, especially if you are pregnant, nursing, take medication or have a medical condition.